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Temprano A, Sanchez de Blas B, Pérez-Melero C, Espinosa-Escudero R, Briz O, Cinca-Fernando P, Llera L, Monte MJ, Bermejo-Gonzalez FA, Marin JJ, Romero MR. Synthesis, Characterization, and Potential Usefulness in Liver Function Assessment of Novel Bile Acid Derivatives with Near-Infrared Fluorescence (NIRBAD). Bioconjug Chem 2024; 35:971-980. [PMID: 38958375 PMCID: PMC11261600 DOI: 10.1021/acs.bioconjchem.4c00168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/21/2024] [Accepted: 06/25/2024] [Indexed: 07/04/2024]
Abstract
Conventional serum markers often fail to accurately detect cholestasis accompanying many liver diseases. Although elevation in serum bile acid (BA) levels sensitively reflects impaired hepatobiliary function, other factors altering BA pool size and enterohepatic circulation can affect these levels. To develop fluorescent probes for extracorporeal noninvasive hepatobiliary function assessment by real-time monitoring methods, 1,3-dipolar cycloaddition reactions were used to conjugate near-infrared (NIR) fluorochromes with azide-functionalized BA derivatives (BAD). The resulting compounds (NIRBADs) were chromatographically (FC and PTLC) purified (>95%) and characterized by fluorimetry, 1H NMR, and HRMS using ESI ionization coupled to quadrupole TOF mass analysis. Transport studies using CHO cells stably expressing the BA carrier NTCP were performed by flow cytometry. Extracorporeal fluorescence was detected in anesthetized rats by high-resolution imaging analysis. Three NIRBADs were synthesized by conjugating alkynocyanine 718 with cholic acid (CA) at the COOH group via an ester (NIRBAD-1) or amide (NIRBAD-3) spacer, or at the 3α-position by a triazole link (NIRBAD-2). NIRBADs were efficiently taken up by cells expressing NTCP, which was inhibited by taurocholic acid (TCA). Following i.v. administration of NIRBAD-3 to rats, liver uptake and consequent release of NIR fluorescence could be extracorporeally monitored. This transient organ-specific handling contrasted with the absence of release to the intestine of alkynocyanine 718 and the lack of hepatotropism observed with other probes, such as indocyanine green. NIRBAD-3 administration did not alter serum biomarkers of hepatic and renal toxicity. NIRBADs can serve as probes to evaluate hepatobiliary function by noninvasive extracorporeal methods.
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Affiliation(s)
- Alvaro
G. Temprano
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
| | - Beatriz Sanchez de Blas
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
- Center
for the Study of Liver and Gastrointestinal Diseases (CIBEREHD), Carlos III National Institute of Health, Madrid 28029, Spain
| | - Concepción Pérez-Melero
- Pharmaceutical
Chemistry Laboratory, Pharmaceutical Sciences Department, University of Salamanca, IBSAL, Salamanca 37007, Spain
| | - Ricardo Espinosa-Escudero
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
| | - Oscar Briz
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
- Center
for the Study of Liver and Gastrointestinal Diseases (CIBEREHD), Carlos III National Institute of Health, Madrid 28029, Spain
| | - Paula Cinca-Fernando
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
| | - Lucia Llera
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
| | - Maria J. Monte
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
- Center
for the Study of Liver and Gastrointestinal Diseases (CIBEREHD), Carlos III National Institute of Health, Madrid 28029, Spain
| | | | - Jose J.G. Marin
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
- Center
for the Study of Liver and Gastrointestinal Diseases (CIBEREHD), Carlos III National Institute of Health, Madrid 28029, Spain
| | - Marta R. Romero
- Experimental
Hepatology and Drug Targeting (HEVEPHARM), University of Salamanca, IBSAL, Salamanca 37007, Spain
- Center
for the Study of Liver and Gastrointestinal Diseases (CIBEREHD), Carlos III National Institute of Health, Madrid 28029, Spain
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Özvegy-Laczka C, Ungvári O, Bakos É. Fluorescence-based methods for studying activity and drug-drug interactions of hepatic solute carrier and ATP binding cassette proteins involved in ADME-Tox. Biochem Pharmacol 2023; 209:115448. [PMID: 36758706 DOI: 10.1016/j.bcp.2023.115448] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/31/2023] [Accepted: 02/01/2023] [Indexed: 02/11/2023]
Abstract
In humans, approximately 70% of drugs are eliminated through the liver. This process is governed by the concerted action of membrane transporters and metabolic enzymes. Transporters mediating hepatocellular uptake of drugs belong to the SLC (Solute carrier) superfamily of transporters. Drug efflux either toward the portal vein or into the bile is mainly mediated by active transporters of the ABC (ATP Binding Cassette) family. Alteration in the function and/or expression of liver transporters due to mutations, disease conditions, or co-administration of drugs or food components can result in altered pharmacokinetics. On the other hand, drugs or food components interacting with liver transporters may also interfere with liver function (e.g., bile acid homeostasis) and may even cause liver toxicity. Accordingly, certain transporters of the liver should be investigated already at an early stage of drug development. Most frequently radioactive probes are applied in these drug-transporter interaction tests. However, fluorescent probes are cost-effective and sensitive alternatives to radioligands, and are gaining wider application in drug-transporter interaction tests. In our review, we summarize our current understanding about hepatocyte ABC and SLC transporters affected by drug interactions. We provide an update of the available fluorescent and fluorogenic/activable probes applicable in in vitro or in vivo testing of these ABC and SLC transporters, including near-infrared transporter probes especially suitable for in vivo imaging. Furthermore, our review gives a comprehensive overview of the available fluorescence-based methods, not directly relying on the transport of the probe, suitable for the investigation of hepatic ABC or SLC-type drug transporters.
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Affiliation(s)
- Csilla Özvegy-Laczka
- Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117 Budapest, Magyar tudósok krt. 2., Hungary.
| | - Orsolya Ungvári
- Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117 Budapest, Magyar tudósok krt. 2., Hungary; Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Éva Bakos
- Institute of Enzymology, RCNS, Eötvös Loránd Research Network, H-1117 Budapest, Magyar tudósok krt. 2., Hungary
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Automated GMP Production and Preclinical Evaluation of [ 68Ga]Ga-TEoS-DAZA and [ 68Ga]Ga-TMoS-DAZA. Pharmaceutics 2022; 14:pharmaceutics14122695. [PMID: 36559188 PMCID: PMC9783202 DOI: 10.3390/pharmaceutics14122695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 12/04/2022] Open
Abstract
[68Ga]Ga-TEoS-DAZA and [68Ga]Ga-TMoS-DAZA are two novel radiotracers suitable for functional PET liver imaging. Due to their specific liver uptake and biliary excretion, the tracers may be applied for segmental liver function quantification, gall tree imaging and the differential diagnosis of liver nodules. The purpose of this study was to investigate problems that occurred initially during the development of the GMP compliant synthesis procedure and to evaluate the tracers in a preclinical model. After low radiolabeling yields were attributed to precursor instability at high temperatures, an optimized radiolabeling procedure was established. Quality controls were in accordance with Ph. Eur. requirements and gave compliant results, although the method for the determination of the 68Ga colloid is partially inhibited due to the presence of a radioactive by-product. The determination of logP revealed [68Ga]Ga-TEoS-DAZA (ethoxy bearing) to be more lipophilic than [68Ga]Ga-TMoS-DAZA (methoxy bearing). Accordingly, biodistribution studies in an in ovo model showed a higher liver uptake for [68Ga]Ga-TEoS-DAZA. In dynamic in ovo PET imaging, rapid tracer accumulation in the liver was observed. Similarly, the activity in the intestines rose steadily within the first hour p.i., indicating biliary excretion. As [68Ga]Ga-TEoS-DAZA and [68Ga]Ga-TMoS-DAZA can be prepared according to GMP guidelines, transition into the early clinical phase is now possible.
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Synthesis and biological activity evaluation of podophyllotoxin- linked bile acid derivatives as potential anti-liver cancer agents. Bioorg Chem 2022; 128:106066. [DOI: 10.1016/j.bioorg.2022.106066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 07/22/2022] [Accepted: 07/27/2022] [Indexed: 11/24/2022]
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Leuenberger M, Häusler S, Höhn V, Euler A, Stieger B, Lochner M. Characterization of Novel Fluorescent Bile Salt Derivatives for Studying Human Bile Salt and Organic Anion Transporters. J Pharmacol Exp Ther 2021; 377:346-357. [PMID: 33782042 DOI: 10.1124/jpet.120.000449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/23/2021] [Indexed: 11/22/2022] Open
Abstract
Bile salts, such as cholate, glycocholate, taurocholate, and glycochenodeoxycholate, are taken up from the portal blood into hepatocytes via transporters, such as the Na+-taurocholate-cotransporting polypeptide (NTCP) and organic anion-transporting polypeptides (OATPs). These bile salts are later secreted into bile across the canalicular membrane, which is facilitated by the bile salt export pump (BSEP). Apart from bile salt transport, some of these proteins (e.g., OATPs) are also key transporters for drug uptake into hepatocytes. In vivo studies of transporter function in patients by using tracer compounds have emerged as an important diagnostic tool to complement classic liver parameter measurements by determining dynamic liver function both for diagnosis and monitoring progression or improvement of liver diseases. Such approaches include use of radioactively labeled bile salts (e.g., for positron emission tomography) and fluorescent bile salt derivatives or dyes (e.g., indocyanine green). To expand the list of liver function markers, we synthesized fluorescent derivatives of cholic and chenodeoxycholic acid by conjugating small organic dyes to the bile acid side chain. These novel fluorescent probes were able to block substrate transport in a concentration-dependent manner of NTCP, OATP1B1, OATP1B3, OATP2B1, BSEP, and intestinal apical sodium-dependent bile salt transporter (ASBT). Whereas the fluorescent bile acid derivatives themselves were transported across the membrane by OATP1B1, OATP1B3, and OATP2B1, they were not transport substrates for NTCP, ASBT, BSEP, and multidrug resistance-related protein 2. Accordingly, these novel fluorescent bile acid probes can potentially be used as imaging agents to monitor the function of OATPs. SIGNIFICANCE STATEMENT: Synthetic modification of common bile acids by attachment of small organic fluorescent dyes to the bile acid side chain resulted in bright, fluorescent probes that interact with hepatic and intestinal organic anion [organic anion-transporting polypeptide (OATP) 1B1, OATP1B3, OATP2B1], bile salt uptake (Na+-taurocholate-cotransporting polypeptide, apical sodium-dependent bile salt transporter), and bile salt efflux (bile salt export pump, multidrug resistance-related protein 2) transporters. Although the fluorescent bile salt derivatives are taken up into cells via the OATPs, the efflux transporters do not transport any of them but one.
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Affiliation(s)
- Michele Leuenberger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
| | - Stephanie Häusler
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
| | - Vera Höhn
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
| | - Adriana Euler
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
| | - Bruno Stieger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
| | - Martin Lochner
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland (M.Le., M.Lo.); Department of Clinical Pharmacology and Toxicology, University Hospital Zürich, Zürich, Switzerland (S.H., V.H., A.E., B.S.); and Swiss National Center of Competence in Research, NCCR TransCure, Bern, Switzerland (M.Le., S.H., A.E., B.S., M.Lo.)
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Metal-Based Complexes as Pharmaceuticals for Molecular Imaging of the Liver. Pharmaceuticals (Basel) 2019; 12:ph12030137. [PMID: 31527492 PMCID: PMC6789861 DOI: 10.3390/ph12030137] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 12/13/2022] Open
Abstract
This article reviews the use of metal complexes as contrast agents (CA) and radiopharmaceuticals for the anatomical and functional imaging of the liver. The main focus was on two established imaging modalities: magnetic resonance imaging (MRI) and nuclear medicine, the latter including scintigraphy and positron emission tomography (PET). The review provides an overview on approved pharmaceuticals like Gd-based CA and 99mTc-based radiometal complexes, and also on novel agents such as 68Ga-based PET tracers. Metal complexes are presented by their imaging modality, with subsections focusing on their structure and mode of action. Uptake mechanisms, metabolism, and specificity are presented, in context with advantages and limitations of the diagnostic application and taking into account the respective imaging technique.
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Frisch K, Kjærgaard K, Horsager J, Schacht AC, Munk OL. Human biodistribution, dosimetry, radiosynthesis and quality control of the bile acid PET tracer [N-methyl- 11C]cholylsarcosine. Nucl Med Biol 2019; 72-73:55-61. [PMID: 31330413 DOI: 10.1016/j.nucmedbio.2019.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/12/2019] [Accepted: 07/11/2019] [Indexed: 01/07/2023]
Abstract
INTRODUCTION [N-methyl-11C]cholylsarcosine ([11C]CSar) is a tracer for imaging and quantitative assessment of intrahepatic cholestatic liver diseases and drug-induced cholestasis by positron emission tomography (PET). The purpose of this study is to determine whole-body biodistribution and dosimetry of [11C]CSar in healthy humans. The results are compared with findings in a patient with primary sclerosing cholangitis (PSC) and a patient with primary biliary cholangitis (PBC) as well as with preclinical findings in pigs. Radiosynthesis and quality control for preparation of [11C]CSar for clinical use are also presented. METHODS Radiosynthesis and quality control of [11C]CSar were set up in compliance with Danish/European regulations. Both healthy participants (3 females, 3 males) and patients underwent whole-body PET/CT to determine the biodistribution of [11C]CSar. The two patients were under treatment with ursodeoxycholic acid at the time of the study. Dosimetry was estimated from the PET data using the Olinda 2.0 software. RESULTS The radiosynthesis provided [11C]CSar in a solution ready for injection. The biodistribution studies revealed that gallbladder wall, small intestine, and liver were critical organs in both healthy participants and patients with the gallbladder wall receiving the highest dose (up to 0.5 mGy/MBq). The gender-averaged (±SD) effective dose for the healthy participants was 6.2 ± 1.4 μSv/MBq. The effective dose for the PSC and the PBC patient was 5.2 and 7.0 μSv/MBq, respectively. CONCLUSION A radiosynthesis for preparation of [11C]CSar for clinical use was developed and approved by the Danish Medicines Agency. The most critical organ was the gallbladder wall although the amount of [11C]CSar in the gallbladder was found to vary significantly between individuals. The estimated effective dose for humans was comparable to that estimated in anesthetized pigs although the absorbed dose estimates to some organs, such as the stomach, was different. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: [11C]CSar PET/CT enables detailed quantitative assessment of patients with cholestatic liver disease by tracing the separate hepatobiliary transport steps of endogenous bile acids. The present work offers a radiosynthetic method and dosimetry data suitable for clinical implementation of [11C]CSar.
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Affiliation(s)
- Kim Frisch
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark.
| | - Kristoffer Kjærgaard
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark; Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Jacob Horsager
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Anna Christina Schacht
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Ole Lajord Munk
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
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Yagi Y, Kimura H, Okuda H, Ono M, Nakamoto Y, Togashi K, Saji H. Evaluation of [18F]pitavastatin as a positron emission tomography tracer for in vivo organic transporter polypeptide function. Nucl Med Biol 2019; 74-75:25-31. [DOI: 10.1016/j.nucmedbio.2019.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 12/28/2022]
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Validation of hepatobiliary transport PET imaging in liver function assessment: Evaluation of 3β-[ 18F]FCA in mouse models of liver disease. Nucl Med Biol 2018; 68-69:40-48. [PMID: 30595544 DOI: 10.1016/j.nucmedbio.2018.12.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/09/2018] [Accepted: 12/03/2018] [Indexed: 12/17/2022]
Abstract
Recently, our research group reported on the development of 3β-[18F]Fluorocholic acid (3β-[18F]FCA), a 18F labeled bile acid to detect drug interference with the bile acid transporters (drug-induced cholestasis). It was hypothesized that 3β-[18F]FCA could also be used as a non-invasive tool to monitor (regional) liver function in vivo in different liver diseases through altered expression of bile acid transporters. METHODS Hepatobiliary transport of 3β-[18F]FCA was evaluated in four murine liver disease models. Acute liver injury was induced by oral gavage of an acetaminophen (APAP) overdose (300 mg/kg). Chronic cholangiopathy and non-alcoholic steatohepatitis (NASH) were induced by feeding mice 3,5-diethoxycarbonyl- 1,4-dihydrocollidine (DDC) diet or methionine and choline deficient (MCD) diet, respectively. Hepatocellular carcinoma (HCC) was evoked by intraperitoneal injection of 35 mg/kg diethylnitrosamine (DEN) once a week for 23 weeks. Gene expression of the murine bile acid transporters was determined by RT-qPCR. RESULTS Hepatobiliary transport of 3β-[18F]FCA was not significantly altered after an APAP overdose. Mice fed the DDC or MCD diet showed impaired transport of 3β-[18F]FCA compared to baseline, which was associated with altered expression of the bile acid transporters ntcp, oatp4 and mrp2. After recovery from DDC- and MCD-induced liver injury, 3β-[18F]FCA parameters returned to baseline. Global hepatobiliary transport of 3β-[18F]FCA in HCC bearing mice was not significantly different compared to control mice. However, HCC lesions showed reduced hepatic uptake of the tracer (tumor-to-background: 0.45 ± 0.13), which was in line with decreased in expression of basolateral bile acid uptake transporters nctp and oatp4 in tumor tissue. CONCLUSION 3β-[18F]FCA is a useful tool to assess and longitudinally follow-up liver function in several mouse models for liver diseases that are associated with altered expression of the bile acid transporters. These results point towards the (pre)clinical utility of 3β-[18F]FCA as a PET tracer to monitor altered liver functionality in patients with chronic liver diseases.
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Human OATP1B1 (SLCO1B1) transports sulfated bile acids and bile salts with particular efficiency. Toxicol In Vitro 2018; 52:189-194. [DOI: 10.1016/j.tiv.2018.06.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 06/12/2018] [Accepted: 06/18/2018] [Indexed: 10/28/2022]
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Preclinical Evaluation of [ 18F]LCATD as a PET Tracer to Study Drug-Drug Interactions Caused by Inhibition of Hepatic Transporters. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:3064751. [PMID: 30154685 PMCID: PMC6091370 DOI: 10.1155/2018/3064751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/28/2018] [Accepted: 05/06/2018] [Indexed: 12/12/2022]
Abstract
The bile acid analogue [18F]LCATD (LithoCholic Acid Triazole Derivative) is transported in vitro by hepatic uptake transporters such as OATP1B1 and NTCP and efflux transporter BSEP. In this in vivo “proof of principle” study, we tested if [18F]LCATD may be used to evaluate drug-drug interactions (DDIs) caused by inhibition of liver transporters. Hepatic clearance of [18F]LCATD in rats was significantly modified upon coadministration of rifamycin SV or sodium fusidate, which are known to inhibit clinically relevant uptake transporters (OATP1B1, NTCP) and canalicular hepatic transporters (BSEP) in humans. Treatment with rifamycin SV (total dose 62.5 mg·Kg−1) reduced the maximum radioactivity of [18F]LCATD recorded in the liver from 14.2 ± 0.8% to 10.2 ± 0.9% and delayed t_max by 90 seconds relative to control rats. AUCliver 0–5 min, AUCbile 0–10 min and hepatic uptake clearance CLuptake,in vivo of rifamycin SV treated rats were significantly reduced, whereas AUCliver 0–30 min was higher than in control rats. Administration of sodium fusidate (30 mg·Kg−1) inhibited the liver uptake of [18F]LCATD, although to a lesser extent, reducing the maximum radioactivity in the liver to 11.5 ± 0.3%. These preliminary results indicate that [18F]LCATD may be a good candidate for future applications as an investigational tracer to evaluate altered hepatobiliary excretion as a result of drug-induced inhibition of hepatic transporters.
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Frisch K, Stimson DHR, Venkatachalam T, Pierens GK, Keiding S, Reutens D, Bhalla R. N-(4-[ 18F]fluorobenzyl)cholylglycine, a novel tracer for PET of enterohepatic circulation of bile acids: Radiosynthesis and proof-of-concept studies in rats. Nucl Med Biol 2018; 61:56-62. [PMID: 29783201 DOI: 10.1016/j.nucmedbio.2018.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/20/2018] [Accepted: 04/27/2018] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Enterohepatic circulation (EHC) of conjugated bile acids is an important physiological process crucial for regulation of intracellular concentrations of bile acids and their function as detergents and signal carriers. Only few bile acid-derived imaging agents have been synthesized and hitherto none have been evaluated for studies of EHC. We hypothesized that N-(4-[18F]fluorobenzyl)cholylglycine ([18F]FBCGly), a novel fluorine-18 labeled derivative of endogenous cholylglycine, would be a suitable tracer for PET of the EHC of conjugated bile acids, and we report here a radiosynthesis of [18F]FBCGly and a proof-of-concept study by PET/MR in rats. METHODS A radiosynthesis of [18F]FBCGly was developed based on reductive alkylation of glycine with 4-[18F]fluorobenzaldehyde followed by coupling to cholic acid. [18F]FBCGly was investigated in vivo by dynamic PET/MR in anesthetized rats; untreated or treated with cholyltaurine or rifampicin. Possible in vivo metabolites of [18F]FBCGly were investigated by analysis of blood and bile samples, and the stability of [18F]FBCGly towards enzymatic de-conjugation by Cholylglycine Hydrolase was tested in vitro. RESULTS [18F]FBCGly was produced with a radiochemical purity of 96% ± 1% and a non-decay corrected radiochemical yield of 1.0% ± 0.3% (mean ± SD; n = 12). PET/MR studies showed that i.v.-administrated [18F]FBCGly underwent EHC within 40-60 min with a rapid transhepatic transport from blood to bile. In untreated rats, the radioactivity concentration of [18F]FBCGly was approximately 15 times higher in bile than in liver tissue. Cholyltaurine and rifampicin inhibited the biliary secretion of [18F]FBCGly. No fluorine-18 metabolites of [18F]FBCGly were observed. CONCLUSION We have developed a radiosynthesis of a novel fluorine-18 labeled bile acid derivative, [18F]FBCGly, and shown by PET/MR that [18F]FBCGly undergoes continuous EHC in rats without metabolizing. This novel tracer may prove useful in PET studies on the effect of drugs or diseases on the EHC of conjugated bile acids.
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Affiliation(s)
- Kim Frisch
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark.
| | - Damion H R Stimson
- Centre for Advanced Imaging, University of Queensland, St. Lucia, Brisbane, Australia
| | - Taracad Venkatachalam
- Centre for Advanced Imaging, University of Queensland, St. Lucia, Brisbane, Australia
| | - Gregory K Pierens
- Centre for Advanced Imaging, University of Queensland, St. Lucia, Brisbane, Australia
| | - Susanne Keiding
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark; Department of Hepatology & Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - David Reutens
- Centre for Advanced Imaging, University of Queensland, St. Lucia, Brisbane, Australia
| | - Rajiv Bhalla
- Centre for Advanced Imaging, University of Queensland, St. Lucia, Brisbane, Australia
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Evaluating Hepatobiliary Transport with 18F-Labeled Bile Acids: The Effect of Radiolabel Position and Bile Acid Structure on Radiosynthesis and In Vitro and In Vivo Performance. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:6345412. [PMID: 29853807 PMCID: PMC5941726 DOI: 10.1155/2018/6345412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 02/12/2018] [Indexed: 11/17/2022]
Abstract
Introduction An in vivo determination of bile acid hepatobiliary transport efficiency can be of use in liver disease and preclinical drug development. Given the increased interest in bile acid Positron Emission Tomography- (PET-) imaging, a further understanding of the impact of 18-fluorine substitution on bile acid handling in vitro and in vivo can be of significance. Methods A number of bile acid analogues were conceived for nucleophilic substitution with [18F]fluoride: cholic acid analogues of which the 3-, 7-, or 12-OH function is substituted with a fluorine atom (3α-[18F]FCA; 7β-[18F]FCA; 12β-[18F]FCA); a glycocholic and chenodeoxycholic acid analogue, substituted on the 3-position (3β-[18F]FGCA and 3β-[18F]FCDCA, resp.). Uptake by the bile acid transporters NTCP and OATP1B1 was evaluated with competition assays in transfected CHO and HEK cell lines and efflux by BSEP in membrane vesicles. PET-scans with the tracers were performed in wild-type mice (n = 3 per group): hepatobiliary transport was monitored and compared to a reference tracer, namely, 3β-[18F]FCA. Results Compounds 3α-[18F]FCA, 3β-[18F]FGCA, and 3β-[18F]FCDCA were synthesized in moderate radiochemical yields (4–10% n.d.c.) and high radiochemical purity (>99%); 7β-[18F]FCA and 12β-[18F]FCA could not be synthesized and included further in this study. In vitro evaluation showed that 3α-FCA, 3β-FGCA, and 3β-FCDCA all had a low micromolar Ki-value for NTCP, OATP1B1, and BSEP. In vivo, 3α-[18F]FCA, 3β-[18F]FGCA, and 3β-[18F]FCDCA displayed hepatobiliary transport with varying efficiency. A slight yet significant difference in uptake and efflux rate was noticed between the 3α-[18F]FCA and 3β-[18F]FCA epimers. Conjugation of 3β-[18F]FCA with glycine had no significant effect in vivo. Compound 3β-[18F]FCDCA showed a significantly slower hepatic uptake and efflux towards gallbladder and intestines. Conclusion A set of 18F labeled bile acids was synthesized that are substrates of the bile acid transporters in vitro and in vivo and can serve as PET-biomarkers for hepatobiliary transport of bile acids.
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Ørntoft NW, Munk OL, Frisch K, Ott P, Keiding S, Sørensen M. Hepatobiliary transport kinetics of the conjugated bile acid tracer 11C-CSar quantified in healthy humans and patients by positron emission tomography. J Hepatol 2017; 67:321-327. [PMID: 28249726 DOI: 10.1016/j.jhep.2017.02.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/23/2017] [Accepted: 02/17/2017] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Hepatobiliary secretion of bile acids is an important liver function. Here, we quantified the hepatic transport kinetics of conjugated bile acids using the bile acid tracer [N-methyl-11C]cholylsarcosine (11C-CSar) and positron emission tomography (PET). METHODS Nine healthy participants and eight patients with varying degrees of cholestasis were examined with 11C-CSar PET and measurement of arterial and hepatic venous blood concentrations of 11C-CSar. RESULTS Results are presented as median (range). The hepatic intrinsic clearance was 1.50 (1.20-1.76) ml blood/min/ml liver tissue in healthy participants and 0.46 (0.13-0.91) in patients. In healthy participants, the rate constant for secretion of 11C-CSar from hepatocytes to bile was 0.36 (0.30-0.62)min-1, 20 times higher than the rate constant for backflux from hepatocytes to blood (0.02, 0.005-0.07min-1). In the patients, rate constant for transport from hepatocyte to bile was reduced to 0.12 (0.006-0.27)min-1, 2.3times higher than the rate constant for backflux to blood (0.05, 0.04-0.09). The increased backflux did not fully normalize exposure of the hepatocyte to bile acids as mean hepatocyte residence time of 11C-CSar was 2.5 (1.6-3.1)min in healthy participants and 6.4 (3.1-23.7)min in patients. The rate constant for transport of 11C-CSar from intrahepatic to extrahepatic bile was 0.057 (0.023-0.11)min-1 in healthy participants and only slightly reduced in patients 0.039 (0.017-0.066). CONCLUSIONS This first in vivo quantification of individual steps involved in the hepatobiliary secretion of a conjugated bile acid in humans provided new insight into cholestatic disease. LAY SUMMARY Positron emission tomography (PET) using the radiolabelled bile acid (11C-CSar) enabled quantification of the individual steps of the hepatic transport of bile acids from blood to bile in man. Cholestasis reduced uptake and secretion and increased backflux to blood. These findings improve our understanding of cholestatic liver diseases and may support therapeutic decisions. CLINICAL TRIAL REGISTRATION NUMBER The trial is registered at ClinicalTrials.gov (NCT01879735).
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Affiliation(s)
- Nikolaj Worm Ørntoft
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Ole Lajord Munk
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Kim Frisch
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Ott
- Department of Hepatology & Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Susanne Keiding
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark; Department of Hepatology & Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Michael Sørensen
- Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark; Department of Hepatology & Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
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Abstract
As the field of PET has expanded and an ever-increasing number and variety of compounds have been radiolabeled as potential in vivo tracers of biochemistry, transporters have become important primary targets or facilitators of radiotracer uptake and distribution. A transporter can be the primary target through the development of a specific high-affinity radioligand: examples are the multiple high-affinity radioligands for the neuronal membrane neurotransmitter or vesicular transporters, used to image nerve terminals in the brain. The goal of a radiotracer might be to study the function of a transporter through the use of a radiolabeled substrate, such as the application of 3-O-[11C]methyl]glucose to measure rates of glucose transport through the blood-brain barrier. In many cases, transporters are required for radiotracer distributions, but the targeted biochemistries might be unrelated: an example is the use of 2-deoxy-2-[18F]FDG for imaging glucose metabolism, where initial passage of the radiotracer through cell membranes requires the action of specific glucose transporters. Finally, there are transporters such as p-glycoprotein that function to extrude small molecules from tissues, and can effectively work against successful uptake of radiotracers. The diversity of structures and functions of transporters, their importance in human health and disease, and their role in therapeutic drug disposition suggest that in vivo imaging of transporter location and function will continue to be a point of emphasis in PET radiopharmaceutical development. In this review, the variety of transporters and their importance for in vivo PET radiotracer development and application are discussed. Transporters have thus joined the other major protein targets such as G-protein coupled receptors, ligand-gated ion channels, enzymes, and aggregated proteins as of high interest for understanding human health and disease.
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Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI.
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